doc: add pricealert doc

README.md

@@ -126,6 +126,8 @@ bbgo pnl --exchange binance --asset BTC --since "2019-01-01"
 
 ## Advanced Configuration
 
+### Notification
+
 - [Setting up Telegram notification](./doc/configuration/telegram.md)
 - [Setting up Slack notification](./doc/configuration/slack.md)
 
@@ -185,7 +187,8 @@ bbgo sync --session binance
 
 Check out the strategy directory [strategy](pkg/strategy) for all built-in strategies:
 
-- `pricealert` strategy demonstrates how to use the notification system [pricealert](pkg/strategy/pricealert)
+- `pricealert` strategy demonstrates how to use the notification system [pricealert](pkg/strategy/pricealert). See
+  [document](./doc/strategy/pricealert.md).
 - `xpuremaker` strategy demonstrates how to maintain the orderbook and submit maker
   orders [xpuremaker](pkg/strategy/xpuremaker)
 - `buyandhold` strategy demonstrates how to subscribe kline events and submit market

doc/configuration/telegram.md

@@ -24,7 +24,7 @@ TELEGRAM_BOT_AUTH_TOKEN=itsme55667788
 ```
  
 The alerting strategies use Telegram bot notification without further configuration. You can check the [pricealert
-yaml file](./config/pricealert-tg.yaml) in the `config/` directory for example.
+yaml file](../../config/pricealert-tg.yaml) in the `config/` directory for example.
 
 If you want the order submitting/filling notification, add the following to your `bbgo.yaml`:
 

doc/strategy/pricealert.md

@@ -0,0 +1,25 @@
+### Price Alert Strategy
+
+This strategy will send notifications to specified channels when the price change of the specified trading pairs is 
+larger than the threshold.
+
+
+### Prerequisite 
+Setup Telegram/Slack notification before using Price Alert Strategy. See [Setting up Telegram Bot Notification
+](../configuration/telegram.md) and [Setting up Slack Notification](../configuration/slack.md).
+
+
+#### Parameters
+
+- `symbol`
+    - The trading pair symbol, e.g., `BTCUSDT`, `ETHUSDT`
+- `interval`
+    - The K-line interval, e.g., `5m`, `1h`
+- `minChange`
+    - Alert threshold, e.g., `100`, `500`. This is a fixed value of price change. Any price change in a single K-line 
+      larger than this value will trigger the alert.  
+
+
+#### Examples
+
+See [pricealert.yaml](../../config/pricealert.yaml) and [pricealert-tg.yaml](../../config/pricealert-tg.yaml)